Disease Note.

First Report of Tomato Yellow Leaf Curl Virus in Portugal. D. Louro, Centro Nacional de Proteccao da Producao Agricola, 2780 Oeiras, Portugal . E. Noris, F. Veratti, and G. P. Accotto, Istituto di Fitovirologia Applicata, CNR, 10135 Torino, Italy. Plant Dis. 80:1079. Accepted for publication 8 July 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-1079D.

In late summer 1995, an epidemic outbreak of a disease associated with the whitefly Bemisia tabaci Genn. seriously affected the tomato (Lycopersicon esculenlum Mill.) crops in Algarve, a region in southern Portugal where tomatoes are cultivated year round. The disease occurred mainly in greenhouse crops and occasionally in open field, with symptoms of general stunting of the plants and leaf curling, with or without yellowing. Autumn crops were severely affected (up to 100%) and yield was drastically reduced. Experimentally, the disease was transmissible by grafting and by whiteflies collected in infected fields. Geminivirus particles were visualized in extracts from infected tomatoes by immunosorbent electron microscopy with antibodies to tomato yellow leaf curl virus (TYLCV-Sr, kindly provided by E. Luisoni). Dot blots were hybridized with DNA probes specific for TYLCVs of different geographical origin (Spain, Sardinia, Sicily, and Israel). A very strong reaction was observed with TYLCV from Israel (I), while only a weak reaction was obtained with the others. Total nucleic acids from infected plants were digested with 15 restriction enzymes selected to help differentiate among TYLCVs. The pattern obtained was compared with that predicted from sequences available for several TYLCVs. The Portuguese TYLCV was similar to two isolates from Israel (EMBL accession nos. XI5656 and X76319) with 12 and 13 enzymes matching, respectively, whereas only 3 enzyme patterns matched with TYLCV from Spain (Z25751) and 4 with TYLCVs from Italy (X6I153 and Z28390). This is the first report of TYLCV in Portugal. So far the disease appears limited to the Algarve region.